Form: grass — perennial
Status: not present in WA
Hymenanche is a native of South and Central America and a Weed of National Significance (WoNS) in Australia.
Appearance
Hymenanche is a stoloniferous, perennial grass which grows from 1-2.5 metres tall. It prefers low lying water on permanent water bodies or seasonally flooded areas. The plant's stems float on water quite successfully. Roots are produced at each node along the stolons where they contact moist soil.
Leaves: Leaves are glossy green in colour, 10-45 centimetres long and are distinguishable by its characteristic stem-clasping leaf bases.
Flowers: Flowers are arranged in cylindrical panicles, 20-40 centimetres long, with spikelets three to five millimetres long. Flowering can occur anytime between September and May, usually during the autumn season.
Seed: Following flowering, large numbers of viable seeds can germinate readily on waterlogged soils.
Agricultural and economic impact
An environmental weed. It primarily invades permanent water bodies and seasonally inundated wetlands, affecting wetlands plant diversity and native animals. Hymenachne invades swamps, wetlands, seasonally flooded areas, waterways, riverbanks, drainage channels and other water bodies. This weed can block waterways, potentially causing flooding and threatening drinking water, and blocks drainage and irrigation channels in cropping areas.
Declared pest category
The Western Australian Organism List (WAOL) contains information on the area(s) in which this pest is declared and the control and keeping categories to which it has been assigned in Western Australia (WA). Search for hymenachne in the WAOL. using the scientific name Hymenachne amplexicaulis.
Requirements for land owners/occupiers and other persons
Requirements for land owners/occupiers and other persons if this pest is found can be sourced through the declared plant requirements link.
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Control method
Control methods for this declared plant can be found through the hymenachne control link.